New-SPWOPIBinding -ServerName owa.contoso.com -AllowHTTP
Get-SPWOPIZone
Set-SPWOPIZone -zone "internal-http"

(Get-SPSecurityTokenServiceConfig).AllowOAuthOverHttp
$config = (Get-SPSecurityTokenServiceConfig)
$config.AllowOAuthOverHttp = $true
$config.Update()
(Get-SPSecurityTokenServiceConfig).AllowOAuthOverHttp

http://technet.microsoft.com/en-us/library/ff431687.aspx